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Alexander, T. W. (1992). Discharge rates for tainter and roller gates at Lock and Dam No 25 on the Mississippi River near Windfield, Missouri. U.S. Geological Survey, Water-Resources Investigations Report 92-4118.

The water surface elevations on the Inland Waterway Navigation System of the Upper Mississippi River are controlled during normal operating conditions by various flow controls located at 29 locks and dams. The headwater (navigation pool) and tailwater elevations at Lock and Dam No. 25 near Windfield, MO, are controlled by the regulation of 14 tainter gates and 3 roller gates. Stage discharge ratings for these tainter and roller gates were developed for use in computing discharge through Dam No. 25 and to aid in regulating the navigation pool within its normal operating limits of 429.70 to 434.00 ft. A total of 57 measurements of discharge that ranged from 370 to 9,220 cu ft/sec were made in the tainter and roller gate forebays. The measured discharges were used to define flow regimes as a function of static-headwater depth (h1), static- tailwater depth (h3), and vertical height of tainter or roller gate opening (hg). Submerged orifice flow is the predominant flow regime at lock and Dam No. 25. Thirty-seven discharge measurements defining coefficients of discharge (Cgs) ranging from 0.087 (hg=1 ft) to 0.731 (hg=14 ft) were used to develop the submerged orifice discharge coefficient relation for the tainter gates. Seventeen discharge measurements defining coefficients of discharge ranging from 0.038 (hg=1 ft) to 0.534 (hg=14 ft) were used to develop the submerged orifice discharge coefficient relation for the roller gates. Also, three discharge measurements were made with the gates closed (hg=0) to evaluate the tainter and roller gate leakage discharge relations. Theoretical equations that express discharge per gate (Q) as a function of discrete hydraulic control variables were developed from these discharge coefficient and gate leakage discharge relations. The resulting equations of discharge area applicable to gate openings of 1 ft to 14 ft and for orifice submergence ratios (h3/hg) ranging from 1.4 to 11.0; thus, these equations can be used to compute discharges for regulated flow conditions not otherwise defined by the current meter discharge measurements. Discharge rating tables for the tainter and roller gates are given for selected combinations of headwater and tailwater elevations.